In thermal printing, as that phrase is used herein, it is generally well known to render images by selectively heating and pressing one or more donor materials such as a dye, colorant or coating against a receiver medium. The donor materials are provided in sized donor patches on a movable web known as a donor ribbon. The donor patches are organized on the donor ribbon in donor patch sets. Each donor patch set contains all of the donor patches that are to be used to record an image on the receiver medium. For full color images, a donor patch set can use multiple patches of differently colored donor material, such as yellow, magenta and cyan donor patches. Arrangements of other color patches can be used in like fashion within a donor patch set. Additionally, each donor patch set can include a clear overcoat or sealant layer.
The size of the donor patches defines the full size of an image that can be printed. Many thermal printers are capable of printing relatively large images such as 6″×8″ images. While prints of this size are highly desirable for many uses, consumers often request that printers render images at a fraction of the full size image, such as images printed at the wallet size, 3″×5″ size or 4″×6″ size. Images at these sizes are more easily used and stored while exhausting only a fraction of the donor material from a donor patch set leaving a fraction donor patch set. Accordingly, many printers are set up to produce only these smaller, more popular standard size prints such as 4″×6″ prints.
Early printers were not adapted to use the remaining donor material from a fractionally used donor patch set for printing other images. Instead, a thermal printer advances the donor ribbon to the next complete donor set after printing a fractional size image so that the thermal printer is prepared to print any size image when the next printing order is received. This results in inefficient use of the donor material and increased printing expense.
A known conventional improvement was to batch together two or more small images for printing at one time, reducing the complete print cycle time. However, if the two images were not printed together, a portion of the donor patch ribbon was not used and was wasted.
Commonly assigned U.S. patent application Ser. No. 11/060,177 entitled SYSTEM AND METHOD FOR EFFICIENT DONOR MATERIAL USE, filed Feb. 17, 2005 in the names of Robert F. Mindler et al.; Ser. No. 11/060,178 entitled SYSTEM AND METHOD FOR EFFICIENT DONOR MATERIAL USE, filed Feb. 17, 2005 in the name of Robert F. Mindler; and Ser. No. 11/192,346 entitled SYSTEM AND METHOD FOR EFFICIENT DONOR MATERIAL USE, filed Jul. 28, 2005 in the names of Anderson et al. disclose methods for individually printing images using donor material from a set of fractional donor patches. This enables more efficient use of donor material and that can do so without requiring costly changes to the printer or to the way in which the printer driver operates.
Thus, there exists a need to efficiently distinguish between complete and incomplete use of the donor patch ribbon when printing fractional size images of, say, 4″×6″ when two sets of 4″×6″ images are not batch together and printed at the same time.